The long-term objective of this research is to characterize mechanisms of interaction of animal cell surface components with each other and with other cellular structures, which are important in regulating cellular processes or in assembling specialized cell surface structures. Our specific aims for this project are (1) to continue our investigation of the mechanism, structural basis, and physiological significance of "anchorage modulation," the inhibition of the lateral mobility of cell surface proteins by concanavalin A, (2) to continue our investigation of the mechanisms of assembly of buds of enveloped viruses on the surfaces of infected cells, (3) to investigate the role of lateral mobility of the b-adrenergic receptor in the activation of adenylate cyclase, (4) to determine the role of lipid fluidity in constraining the lateral diffusion of cell surface proteins, and (5) to make several technical improvements in our procedures for observing cell surface dynamics by fluorescence microscopy. Techniques and phenomena of interest in Biophysics, Biochemicstry, Virology, Immunology, and Cell Biology will be used or explored. Results gained from this research will provide information about molecular mechanisms of the regulation of cellular activities and properties and will be useful in exploring perturbations induced by disease.